M46 Anti-Tank DPICM Submunition
1. Overview
The M46 is an artillery-delivered anti-armor submunition designed to defeat armored vehicles through a powerful shaped charge warhead. Serving as the anti-tank component of the US Dual-Purpose Improved Conventional Munition (DPICM) family, the M46 is loaded alongside the smaller M42 anti-personnel submunitions in cargo projectiles like the M483A1. The M46’s larger shaped charge provides significantly greater armor penetration than the M42, enabling artillery batteries to engage main battle tanks and heavily armored vehicles in addition to lighter targets.
2. Country/Bloc of Origin
- Country: United States of America
- Developer: US Army / Various defense contractors
- Development Period: 1970s
- Service Entry: 1975
- International Users: United States and numerous NATO/allied nations
The M46 was developed to give conventional tube artillery a meaningful anti-armor capability against the massed Soviet tank formations expected in a European conflict.
3. Ordnance Class
| Attribute | Classification |
|---|---|
| Type | Submunition / Bomblet / Grenade |
| Role | Anti-Tank (AT) / Anti-Armor |
| Delivery Method | Artillery-delivered via cargo projectile |
| Category | Improved Conventional Munition (ICM) |
| Target Types | Tanks, APCs, IFVs, armored vehicles |
The M46 is classified as the anti-armor component of the DPICM system, complementing the M42’s anti-personnel role to create a combined-effects artillery capability.
4. Ordnance Family / Nomenclature
Primary Designation:
- M46 (Grenades, Submunition, Anti-Armor)
- M42 (Companion anti-personnel submunition)
Parent Projectiles:
- M483A1 – 155mm DPICM projectile containing 88 submunitions (64 M42, 24 M46)
- M864 – 155mm Base Bleed DPICM with extended range
- M449/M449A1 – Earlier 155mm ICM projectiles
Related Munitions:
- M42 – Companion DPICM submunition (anti-personnel)
- M77 – MLRS DPICM submunition
- BLU-97/B – Air-delivered combined effects submunition
- SADARM – Sensor-fuzed artillery anti-armor munition (more advanced concept)
Common Names:
- DPICM Anti-Armor Grenade
- AT Bomblet
- “Big Bomblet” (relative to M42)
5. Hazards
Primary Hazards
| Hazard Type | Description |
|---|---|
| Shaped Charge | Powerful armor-penetrating jet |
| Fragmentation | Steel body fragments upon detonation |
| Residual Explosive | Undetonated explosive fill in duds |
Shaped Charge Effects
The M46’s primary kill mechanism is its shaped charge:
- Forms high-velocity copper jet upon detonation
- Penetrates armor through hydrodynamic forces
- Behind-armor effects include spall, fire, and crew casualties
- Effective against top armor of most armored vehicles
Sensitivity Factors
- Impact Fuze: All-ways acting, functions on impact
- Dud Sensitivity: Armed duds retain full sensitivity; extremely dangerous
- Ribbon Issues: Tangled stabilization ribbons affect function
- Dud Rate: Historical dud rates create significant UXO hazard
Safety Considerations
- Armor Penetration Capability: Can penetrate vehicle armor and structural materials
- High Dud Rate: Common to artillery submunitions
- Large Warhead: More explosive than M42; greater blast effects
- Delayed Hazard: Duds may function if disturbed long after impact
- Wide Dispersal: Large areas potentially contaminated
Kill/Danger Radius
| Zone | Distance | Effect |
|---|---|---|
| Lethal Radius | ~15 meters | Fatal injuries from fragmentation |
| Casualty Radius | ~25 meters | Significant injury risk |
| Armor Defeat | Direct hit required | Penetration of top/side armor |
| Safety Distance | Minimum 75 meters | From individual dud |
⚠️ WARNING: M46 submunitions contain a powerful shaped charge warhead with significant explosive content. Unexploded bomblets are extremely dangerous and may detonate if touched, moved, or disturbed. The all-ways acting fuze can function at any angle. Never approach any suspected M46 munition.
6. Key Identification Features
Physical Characteristics
| Dimension | Measurement |
|---|---|
| Length | Approximately 11.7 cm (4.6 inches) |
| Diameter | Approximately 5 cm (2.0 inches) |
| Weight | Approximately 400 grams (14 oz) |
Visual Identification
- Shape: Cylindrical body with pronounced conical nose
- Color: Olive drab (OD) green body
- Markings: May have yellow band indicating HE content; nomenclature stenciled
- Material: Steel body
- Distinctive Features:
- Larger than M42 (approximately twice the size)
- More pronounced conical shaped charge nose
- Nylon stabilization ribbon (longer than M42 ribbon)
- Visible copper liner in nose (if damaged)
Size Comparison
| Characteristic | M42 | M46 |
|---|---|---|
| Length | 8.5 cm | 11.7 cm |
| Diameter | 3.8 cm | 5.0 cm |
| Weight | 215g | 400g |
| Visual | Smaller, hemispherical nose | Larger, conical nose |
Stabilization Ribbon
The M46 uses a nylon ribbon for aerodynamic stabilization:
- Longer ribbon than M42 due to greater weight
- Deploys upon ejection from projectile
- Orients submunition nose-down for optimal shaped charge function
- Ribbon may be found extended, wrapped around obstacles, or tangled
Condition Indicators
- Intact: OD green body, conical nose visible, ribbon may be deployed
- Damaged: Deformation, visible internal components, partial fragmentation
- Dud: Appears intact but failed to detonate; extremely dangerous
- Post-Detonation: Fragmented remains, possible small crater, scorch marks
7. Fuzing Mechanisms
Primary Fuze System
The M46 employs an all-ways acting (AWA) impact fuze:
| Component | Function |
|---|---|
| Impact Sensor | Detects impact at any angle |
| All-Ways Acting Mechanism | Ensures function regardless of orientation |
| Firing Circuit | Initiates shaped charge detonator |
| Detonator/Booster | Amplifies initiation to main charge |
Arming Sequence
- Ejection: Projectile base expels submunitions at preset altitude
- Ribbon Deployment: Nylon ribbon deploys, creating aerodynamic drag
- Orientation: Ribbon stabilizes bomblet nose-down
- Arming: Setback and/or rotation arms fuze mechanism
- Descent: Bomblet falls toward target
- Impact: All-ways acting fuze initiates; shaped charge detonates
Safety Mechanisms
- Setback Safety: Requires ejection acceleration
- Arming Delay: Prevents premature detonation during ejection
- Mechanical Locks: Physical barriers removed during arming sequence
All-Ways Acting Principle
The AWA fuze ensures reliable function regardless of impact angle:
- Compensates for non-perpendicular impacts
- Shaped charge effectiveness varies with impact angle but fuze will function
- Critical for area weapons where precise orientation cannot be guaranteed
Dud Fuze Conditions
Unexploded M46 submunitions may exist in various states:
- Unarmed: Failed to complete arming sequence (rare; still dangerous)
- Armed: Fully armed but fuze failed to initiate (most common; extremely dangerous)
- Partially Initiated: Incomplete detonation (very dangerous; sensitive)
Common Dud Causes
- Soft impact surface preventing fuze function
- Ribbon entanglement causing incorrect orientation
- Fuze component failure
- Manufacturing defects
- Environmental conditions during descent
8. History of Development and Use
Development Background
The M46 emerged from the recognition that anti-personnel submunitions alone could not effectively engage the armored threats expected in Cold War scenarios. Adding a dedicated anti-armor submunition to DPICM projectiles gave artillery a genuine capability against tanks without requiring separate anti-armor ammunition types.
Development Timeline
| Year | Event |
|---|---|
| 1970s | Development alongside M42 in DPICM program |
| 1975 | Service entry in M483 series projectiles |
| 1980s | Widespread fielding in NATO artillery units |
| 1991 | Extensive combat use in Gulf War |
| 2003 | Used in Iraq War |
| 2008 | Convention on Cluster Munitions (US did not sign) |
| 2017+ | Ongoing policy reviews |
Tactical Concept
The M46 provides artillery with direct anti-armor effects:
Target Engagement:
- Top-attack against tanks in defensive positions
- Side armor engagement of moving formations
- APCs and IFVs throughout engagement envelope
- Armored self-propelled artillery
- Engineer and recovery vehicles
Employment Methods:
- Massed fires against armored formations
- Final protective fires against tank assaults
- Engagement of assembly areas and staging positions
Combat Use
Operation Desert Storm (1991): DPICM was a primary munition for US and coalition artillery:
- Massive expenditure against Iraqi armored and mechanized units
- Credited with significant vehicle kills and suppression
- Post-war surveys confirmed effectiveness against lighter armor
Operation Iraqi Freedom (2003): Continued DPICM employment against military targets:
- Used in both close support and interdiction roles
- Significant UXO remaining post-conflict
Effectiveness Assessment
The M46’s effectiveness varies by target type:
| Target | M46 Effectiveness |
|---|---|
| Main Battle Tanks | Moderate (top attack only) |
| APCs/IFVs | High |
| Self-Propelled Artillery | High |
| Trucks/Soft Vehicles | Effective (overkill) |
| Personnel | Effective (fragmentation) |
Current Status
- M46 DPICM remains in US inventory
- Subject to policy restrictions on use
- 2022 policy enabled transfer to Ukraine
- Significant UXO contamination in previous conflict zones
- Ongoing development of alternatives (precision artillery)
9. Technical Specifications
Explosive Content
| Specification | Detail |
|---|---|
| Main Charge | Composition B or similar |
| Charge Weight | Approximately 45 grams (1.6 oz) |
| Shaped Charge Liner | Copper (larger than M42) |
| Total Explosive | More than double M42 content |
Warhead Effects
| Effect Type | Capability |
|---|---|
| Shaped Charge Penetration | >150mm (6 inches) RHA at optimal angle |
| Fragmentation | Steel body fragments |
| Behind-Armor Effects | Spall, fire, crew casualties |
Performance Characteristics
| Specification | Detail |
|---|---|
| Armor Penetration | 150mm+ Rolled Homogeneous Armor |
| Effective Against | Tanks (top), APCs, IFVs, SP artillery |
| Function Mode | Impact (all-ways acting) |
| Stabilization | Nylon ribbon drag |
| Optimal Attack Angle | Near-perpendicular (top attack ideal) |
Parent Projectile Configuration
| Projectile | M42 Count | M46 Count | Ratio |
|---|---|---|---|
| M483A1 | 64 | 24 | ~2.7:1 |
| M864 BB | Similar | Configuration | ~2.7:1 |
Comparative Specifications
| Specification | M42 | M46 |
|---|---|---|
| Primary Role | Anti-Personnel | Anti-Armor |
| Armor Penetration | 65mm | 150mm+ |
| Weight | 215g | 400g |
| Explosive Weight | 21g | 45g |
| Quantity per M483A1 | 64 | 24 |
10. Frequently Asked Questions
Q: How effective is the M46 against modern main battle tanks? A: The M46’s effectiveness against modern MBTs is limited to specific conditions. Its 150mm+ penetration can defeat the relatively thin top armor of most tanks, making top-attack trajectories the most effective. However, reactive armor, composite armor arrays, and active protection systems on modern tanks can reduce effectiveness. The M46 is much more effective against the thinner armor of APCs, IFVs, and older tank designs. Against modern MBTs, multiple M46 hits or combination with other anti-armor systems may be required for a kill.
Q: Why are both M42 and M46 loaded in the same projectile? A: The combined loading creates a synergistic effect against mixed enemy formations. Soviet/Russian-style combined arms formations include tanks, infantry fighting vehicles, armored personnel carriers, trucks, self-propelled artillery, and dismounted infantry operating together. The M46 submunitions engage the heavier armored vehicles while the more numerous M42 submunitions suppress and kill infantry, damage lighter vehicles, and cover the larger area. This combination allows a single projectile type to be effective against the full range of targets in a mechanized formation.
Q: How does the M46’s top-attack approach work against armored vehicles? A: Artillery-delivered submunitions achieve top-attack by being ejected at altitude and descending onto targets. Vehicle top armor is typically much thinner than frontal armor—a tank that might have 500mm+ frontal protection often has only 40-80mm on the roof. The M46’s 150mm penetration capability significantly exceeds typical top armor thickness. However, the attack angle is rarely perfectly perpendicular, and moving vehicles may not be hit on the roof. The effectiveness relies on statistical probability: with multiple submunitions covering the target area, some will impact vehicle tops at favorable angles.
Q: What makes M46 UXO particularly dangerous compared to other submunitions? A: The M46 presents enhanced hazards due to its larger explosive content (approximately double the M42), making any detonation more destructive. The shaped charge warhead can penetrate walls, vehicles, and other cover that might protect against smaller bomblets. The all-ways acting fuze means the bomblet can function regardless of how it’s disturbed. Additionally, the larger size might make people believe it’s more stable or easier to handle, when in fact any manipulation of an armed dud is extremely dangerous. The copper liner can also fragment into hazardous projectiles if the shaped charge initiates.
Q: How does weather affect M46 submunition employment? A: Weather impacts M46 employment in several ways: wind affects submunition dispersion patterns and can blow bomblets outside intended target areas; rain, snow, or soft ground cushions impact and increases dud rates; cold temperatures can affect fuze mechanisms and explosive sensitivity; humidity may affect ribbon deployment; and visibility conditions affect target acquisition (though not submunition function). Fire direction calculations attempt to compensate for wind, but small submunitions are significantly affected by atmospheric conditions between ejection altitude and impact.
Q: Can M46 submunitions penetrate fortifications or buildings? A: The M46’s shaped charge is optimized for armor penetration rather than structural defeat, but it can penetrate many building materials. The jet can breach concrete roofs, metal structures, and other hard covers, though effectiveness varies with material thickness and angle. For deliberate fortification attack, conventional HE or specialized concrete-piercing munitions are more effective. However, M46 submunitions landing on lightly-constructed buildings, field fortifications, or exposed positions can penetrate and cause significant damage and casualties inside.
Q: Why doesn’t the US use precision-guided artillery submunitions instead of M46? A: The US has developed precision artillery munitions like Excalibur (GPS-guided) and sensor-fuzed weapons like SADARM/BONUS, which offer greater accuracy and lower collateral damage potential. However, these cost significantly more per round—precision rounds cost tens of thousands of dollars versus hundreds for DPICM. For engaging large area targets, massed enemy formations, or when collateral damage is less of a concern, DPICM remains more cost-effective. The US retains DPICM capability while also fielding precision munitions, selecting based on tactical requirements and policy restrictions.
Q: How do artillerymen ensure M46 submunitions hit armored vehicles rather than empty ground? A: Artillery employment against armored targets combines several factors: intelligence and reconnaissance identify target locations and dispositions; multiple rounds are fired to create overlapping patterns covering the target area; timing is critical—targets should be engaged when stationary or confined (assembly areas, road networks, chokepoints); terrain analysis identifies where vehicles will likely be; and volume of fire compensates for imprecision. The intent is not for every submunition to hit a vehicle, but for enough submunitions to impact vehicles within the target area to achieve the desired effect.
This document is for educational and training purposes only. All ordnance should be treated as dangerous until rendered safe by qualified EOD personnel. Never attempt to handle, move, or disturb any suspected explosive ordnance.